1. Field of Invention
The invention relates to a hinge assembly for use in a tandem pivot structure that has one or more tandem motion locks and a lock override. The hinge assembly is particularly suited for use in a reprographic device having two separately rotatable units provided in a piggyback fashion.
2. Description of Related Art
Printers, copiers, facsimiles and other reprographic products typically have a cover or structural housing that has to be pivoted open to gain access to internal components, such as for ink or toner replenishment, media jams, etc. Copiers and multifunctional printers and devices with printing, scanning and/or copying functions have additional requirements for pivoting covers. Such multifunction devices besides having printing mechanisms may also include scanning mechanisms and may have a feed unit with automatic document feeding mechanisms. The feed unit is normally oriented in a nearly horizontal position. Such feed units must be pivoted open to access a scanner platen glass for document copying or media jam recovery.
The feed unit may be tandemly coupled in piggyback fashion to a lower structure, which incorporates the scanner and also pivots. This lower scanner unit is also normally oriented in a nearly horizontal position. An example of this is shown in simplistic form in FIGS. 1-2. Printer device 100 includes an upper rotatable feed unit 110 coupled to a rotatable lower scanner unit 130 through a first coupling hinge 120. The rotatable lower scanner unit 130 is rotatable relative to the lower base of printer 100 through a second coupling hinge 140. Thus, two tandem hinges are provided that can each be independently rotated. However, when the lower scanner unit 130 is pivoted fully open to provide access to the interior of the printer device 100, a problem may arise as shown in FIG. 2. That is, the upper feeder unit 110 may want to pivot further, possibly falling behind the device due to the influence of gravity and/or inertial motion caused by the opening of the lower scanner unit.
If the lower scanner unit is intended to accommodate books with the upper feeder unit closed, a vertical slide or elevating range can be provided to accommodate the thickness of the book on the scanner unit. Such an elevating capability can create additional problems when the scanner unit is opened fully because now the feeder unit, if not restrained, can extend in translation backwards with undesired force and consequences, due to gravity and momentum.
When an unrestrained feeder unit 110 falls backwards due to pivot motion allowed by the first coupling hinge 120 or by unrestrained translation of an elevating slide, the feeder unit 110 can strike a wall behind the printer device 100, or a person walking behind it. Moreover, when the feeder unit 110 freely falls backwards, the feeder unit 110, first connecting hinge 120 and/or hinge mounting components can be bent or damaged.
All of these problems are brought about due to integration of functions added to printers when they require multipurpose functionality. User interface unpredictability can also be part of the problem. Users of the device may ignore motion tendencies of the various cover mechanisms they are opening. The propensity to be casual and inattentive when opening and handling of the various device units being pivoted can lead to yet another problem. The hinge may not be opened far enough to optimally accomplish the desired task, such as jam removal or ink replenishment.
Accordingly, structures for accommodating tandem pivoting units may suffer from various problems.